Bring on the Bronze

Chris Melrose with the Mariner Shuttle, loaded with gear for gathering data on time and location, salinity, temperature, and dissolved oxygen, counting zooplankton sized particles, measuring the light that penetrates to different depths, and collecting zooplankton that can be counted and identified later in the lab. NOAA/NEFSC photo by Jerry Prezioso

NEFSC’s Dr. Mark Berman with the skeleton of his Bronze medal winning Mariner Shuttle, the first undulating towed body with the capacity for rapidly measuring ocean productivity at minimal operational cost. NOAA/NEFSC photo by Chris Melrose, URI

Once a month, Berman and colleagues tow the Mariner Shuttle in five sections of Narragansett Bay, gathering physical, biological, and chemical data that provide a baseline for assessing changes in the Narragansett Bay ecosystem. Here NEFSC biochemist Elaine Caldarone collects water samples from the bay – the samples will be analyzed for salinity, temperature, dissolved oxygen, and chlorophyll content and used to verify similar data collected by the shuttle. NOAA/NEFSC photo by Mark Berman

Bring on the Bronze
Mariner Shuttle Developer Honored by NOAA

by Teri L. Frady

NEFSC biological oceanographer Mark Berman has won a 2005 NOAA bronze medal for his work adapting a commercially available underwater sled for use as a scientific data gatherer and sampling device. Dubbed the Mariner Shuttle, Berman’s towed submersible is the centerpiece of an ambitious, multi-agency effort to conduct a comprehensive study of the ecology of Narragansett Bay.

Seven years in the making, Berman’s award-winning shuttle is a collection of instruments packed aboard a sled. Towed behind a boat, the shuttle flies underwater, cruising up and down in the water column, taking physical, chemical and biological measurements at the surface and the depths, and in between.

NOAA bronze medals are awarded annually to individuals or groups to recognize superior performance and outstanding or significant contributions that have increased the efficiency and effectiveness of the agency.

Although the Mariner Shuttle gathers data that are being used in a variety of studies, Berman is most interested in what is happening at the base of the marine food chain, where microscopic plants called phytoplankton turn chemicals and light into the food that ultimately feeds all the animals in the Bay.

To understand an ecosystem, scientists need to know how “productive” it is, i.e. how much food is being produced in the system.

The traditional methods for measuring productivity are time-consuming and expensive, Berman explains. Biologists interested in productivity take samples of water and incubate them in the lab. They then measure the activity of their phytoplankton sample and extrapolate their results to come up with a productivity estimate for the whole ecosystem. Scientists using this technique have to make estimates for whole ecosystems based on a very small number of samples.

The Mariner Shuttle allows Berman’s group to measure the rate of photosynthesis as it is occurring in the Bay. One of the instruments aboard the shuttle is a Fast Repetition Rate Fluorometer, a device that sends out as many as 120 flashes of light per second. Some of the light is absorbed by phytoplankton and used in photosynthesis. By measuring the amount of light that is reflected back unused, Berman and post-doctoral fellow Chris Melrose can determine how much photosynthesis is going on in the waters the shuttle is passing through. Using this technique, the NEFSC scientists can measure productivity once per second, gathering a much larger set of data on which to estimate the whole ecosystem’s productivity.

While the shuttle is already a medal-winning craft, it remains a work in progress. The next step is installing a miniature nutrient analyzer that will provide real-time measurements of nitrate, nitrite, silicate, phosphate and other life-supporting nutrients in the water.

The Mariner Shuttle’s cruises so far have been limited to Narragansett Bay, but other crafts based on the Mariner Shuttle are being built for studies in the Yellow Sea and waters off South Africa, Namibia, and Angola.

Berman hopes to take the shuttle into offshore .waters. In one proposed study, the shuttle would work in conjunction with NOAA and NASA satellites that NEFSC biologist John O’Reilly uses to estimate ocean productivity based on the color of the water. The shuttle would provide field checks for the estimates by measuring surface activity in specific areas, and would flesh out the estimates by measuring productivity beneath the water’s surface, where satellites can’t see.

Although Berman’s bronze medal is an individual award, the Narragansett scientist also cites a small band of Mariner Shuttle collaborators: URI post-doc Melrose, biochemist Elaine Caldarone, electronics technician Ron Guilmette, biologist Jack Jossi – and, of course, Narragansett Laboratory director Kenneth Sherman. “We couldn’t have done any of this work without Ken’s support,” Berman says.

The other entities collaborating with the NOAA Fisheries Narragansett Laboratory in the study of the Narragansett Bay ecosystem include Rhode Island Department of Environmental Management, the University of Rhode Island, Roger Williams University, Narragansett Bay National Estuarine Research Reserve, and the United States Environmental Protection Agency.

Posted March 20, 2006